This example visualizes budget data by service category over time using an area chart. The interactive tooltip, appearing on hover, reveals the total budget for each service in a given year. The visualization is built with the Vega-Lite API, which programmatically constructs the chart specification. The code loads CSV data from a GitHub URL, binds the renderer to an SVG view, and configures the dark theme and axis styling. It also leverages the vega-tooltip library's `Handler` for interactive feedback.